Synergies come primarily from cost reductions and cost avoidance. Only new synergies - not cumulative synergies -- are taken into account every year.

Renault and Nissan collaboration increased worldwide, particularly in emerging markets where both companies are expanding their industrial footprints.

"Synergies and greater economies of scale allow Renault and Nissan to compete in an elite tier of the world's top automakers globally," said Christian Mardrus, Renault-Nissan Alliance Managing Director for Logistics and the Office of the CEO. "We expect to generate even more synergies going forward, particularly in emerging markets such as Brazil, Russia, India and China."

As in previous years, the top contributors to synergies by business unit in 2012 were purchasing (851 million euros), powertrain (709 million euros) and vehicle engineering (546 million euros).

Synergies increasingly come from Asia and emerging markets such as Russia, where the two manufacture vehicles and powertrains together at the same plants.

The Alliance's plant in Chennai, India, for example, is home to the biggest platform-sharing project within the Alliance. The plant, which has an annual production capacity of 400,000 units, produces both Renault and Nissan vehicles for export and the local market.